R. O. Erickson (1943) separated the Missouri plants as Clematis fremontii var. riehlii R. O. Erickson on the basis of their supposedly greater height and more widely spaced, proportionately narrower leaves. As noted by C. S. Keener (1967), however, so much overlap occurs in the ranges of variation of the Missouri and the Kansas-Nebraska populations that recognition of these varieties is not possible.